Abstract:It is well known that the effectiveness of a trailing-edge control surface can be substantially diminished due to the elastic twist of an airfoil or wing. This aeroelastic phenomenon is known as control surface reversal when the lift or roll rate vanishes at a sufficiently large ratio of flow dynamic pressure to wing stiffness. However, a leading-edge control surface can be used to counteract control surface reversal, and indeed, in principle, a leading-edge control surface may entirely cancel the tendency of the trailing-edge control surface to undergo reversal. Moreover, analysis shows that by using a simple control strategy one can use a combination of leading- and trailing-edge control surface rotations to maintain lift and roll effectiveness and minimize control surface rotations. The beneficial effects of leading-edge control surfaces on control surface reversal are known to practioners. However, the present simple model makes these especially transparent and suggests an advantageous strategy using a combination of leading- and trailing-edge control surfaces.